Method for recycling impurity removal wastewater in rare earth smelting separation process

Abstract

The invention discloses a recycling method of impurity-removed wastewater in a rare earth smelting separation process, which comprises the following steps: neutralizing the wastewater generated in the rare earth smelting separation process by using calcium oxide, controlling the pH value to be greater than or equal to 7, removing non-rare earth ions in the wastewater, and filtering to obtain calcium-containing filtrate; and extracting the filtrate by using an extracting agent to remove calcium, and recycling the filtrate without calcium to a leaching process in a rare earth smelting separation process. According to the method, iron, zinc and calcium ions influencing rare earth smelting separation in the washing water can be removed, saponification is avoided during calcium ion removal, and the treated wastewater is directly reused in the leaching process of the sulfuric acid rare earth roasted ore.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for recycling impurity-removing waste water in a rare earth smelting and separation process. Background Art

[0002] During the rare earth smelting and separation process, the rare earth solution contains impurities such as iron and zinc. Since the product quality standards have strict requirements on impurities, the extraction method is more effective in removing them. The industry generally uses amine extractants for extraction. The loaded organic matter after extraction is stripped and regenerated with low-acid water, thus producing wastewater containing iron and zinc. The traditional way to treat wastewater is to discharge it directly or incorporate it into industrial ammonium chloride wastewater for evaporation treatment. This process consumes a lot of energy and is costly.

[0003] The Chinese patent application with publication number CN105461002A discloses a method for removing calcium and magnesium from rare earth industrial wastewater. The ammonium sulfate wastewater produced by the rare earth acid smelting process is used as the treatment object, 50% by volume of P507 plus 50% by volume of sulfonated kerosene are used as organic extractants, and extraction is carried out under the conditions of an organic phase to liquid phase volume ratio of 1 to 2 and a saponification rate of 45% to 60%, and the extraction is allowed to stand for stratification.

[0004] The patent application of China Publication No. CN106906361A discloses a method for removing calcium and magnesium by extraction instead of chemical method. P204 organic phase is saponified with sodium hydroxide, and the pH value is adjusted according to the relationship between the extraction rate of P204 for various metals and the equilibrium pH, and the extraction series is controlled to extract iron, zinc, calcium, manganese and other impurities from the cobalt-tin solution. Calcium, copper, manganese and zinc are loaded into the organic phase, and then stripped with hydrochloric acid to form calcium chloride, copper, manganese and zinc solution. Cobalt, nickel and magnesium enter the raffinate and enter the next process. The cobalt-nickel separation line is far away, and cobalt enters the P507 loaded organic phase. Nickel and magnesium enter the raffinate, and the loaded organic phase is stripped to form a cobalt chloride solution.

[0005] The paper "Research on the Deep Purification Process of Crude Nickel Sulfate as a Byproduct of Copper Electrolysis" studied the deep purification of crude nickel sulfate solution using Na2S2O3 selective precipitation of copper-extraction deep removal of zinc and iron-evaporation crystallization process, and optimized the key process parameters. The results show that when Na2S2O3 is used as a precipitant, under the optimal process conditions of Na2S2O3 excess coefficient 2.0, solution pH = 5.0, reaction temperature 85℃, and reaction time 2h, the Cu precipitation rate can reach 99.89%, and the Ni loss rate is only 1.22%; when P204 is selected as an extractant, under the optimal process conditions of controlling the extract solution pH = 3.0, P 204 Volume fraction 25%, saponification rate 50%, compared with V O / V A=1.5 / 1, extraction temperature 25℃, extraction time 10min, the extraction rates of Zn and Fe can reach 99.87% and 99.98% respectively, and the Ni loss rate is 2.24%. The deeply purified nickel sulfate solution is evaporated and crystallized to obtain electroplating grade nickel sulfate crystals.

[0006] At present, the ammonium sulfate wastewater produced by the rare earth acid smelting process is treated by saponification to remove calcium and magnesium. Similarly, the saponification reaction is also used to purify the crude nickel sulfate solution. This wastewater treatment process consumes a lot of water, and the wastewater after impurities removal cannot be reused. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recycling impurity-removing wastewater in the process of rare earth smelting and separation, to remove iron, zinc and calcium ions in the washing water that affect the rare earth smelting and separation, without saponification when removing calcium ions, and the treated wastewater is directly reused in the leaching process of rare earth sulfate roasting ore.

[0008] To achieve the above purpose, the technical solution used in the present invention is:

[0009] The recycling method of impurity removal wastewater in the rare earth smelting and separation process includes:

[0010] Use calcium oxide to neutralize the wastewater generated during the rare earth smelting and separation process, control the pH value to ≥7, remove non-rare earth ions, and obtain a calcium-containing filtrate after filtration;

[0011] The filtrate is extracted with an extractant to remove calcium, and the filtrate from which calcium has been removed is recycled to the leaching process of the rare earth smelting and separation process.

[0012] Furthermore, the content of iron and zinc impurities in the wastewater was analyzed, with a focus on monitoring the content of calcium and magnesium.

[0013] Furthermore, the wastewater is wash water mainly containing chloride ions, iron ions and zinc ions generated during the rare earth smelting and separation process.

[0014] Furthermore, during the neutralization process of wastewater containing iron and zinc, calcium oxide is slowly added to the wastewater containing iron and zinc, and the pH value of the solution is monitored at the same time. After the pH value is qualified, the addition of calcium oxide is stopped, and the calcium oxide neutralization method is adopted to remove non-rare earth ions in the wastewater by controlling the pH of the reaction process, and the impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitates.

[0015] Further, the pH value is 7-11.

[0016] Further, the hydroxide precipitate includes: Fe(OH)3 and Zn(OH)2.

[0017] Further, P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process.

[0018] Furthermore, the organic phase loaded with calcium ions is stripped and washed by using hydrochloric acid to form a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0019] Further, P 204 Concentration = 1-1.8 mol / L, filtrate: organic phase ratio = 1:1-10:1, hydrochloric acid concentration = 2-8 mol / L.

[0020] Furthermore, the content of impurities iron and zinc in the filtrate after calcium removal is analyzed, and if qualified, it is recycled to the leaching process of rare earth sulfate roasted ore.

[0021] The technical effects of the present invention include:

[0022] 1. The present invention treats the iron- and zinc-containing wastewater generated in the rare earth production process, and successively undergoes water washing and neutralization, extraction and calcium removal processes. The treated wastewater is directly reused in the leaching process of rare earth sulfate roasted ore.

[0023] The wastewater treated by the present invention is wash water (wastewater) mainly containing chloride ions, iron ions and zinc ions generated in the process of rare earth smelting and separation. The iron, zinc and calcium ions that affect the rare earth smelting and separation are removed from the wash water. The calcium ions are removed without saponification. The treated wastewater is directly reused in the leaching process of the rare earth sulfate roasting ore.

[0024] 2. Reduce water consumption and drainage in the rare earth production process, realize the comprehensive utilization of water resources, and reduce pollution to the surrounding environment.

[0025] This application performs two-step purification on iron- and zinc-containing wastewater to remove iron, zinc and calcium ions in the wash water that affect rare earth smelting and separation, so that the purified wash water can be reused in the rare earth smelting and separation process. This reduces the amount of water and water discharged during rare earth production and achieves comprehensive utilization of water resources. It can also reduce surrounding environmental pollution and improve environmental quality.

[0026] 3. The extraction agent used in the process of extraction and decalcification is P 204 , and P 507 Compared with other products, its advantage is that it does not saponify when removing calcium ions, 204 Extraction capacity is greater than P 507 , no new impurities are introduced, the cost is low, no waste water is generated, the extraction method is simple to operate, and continuity can be achieved.

[0027] 4. The whole process is simple to operate, convenient, fast and economical.

[0028] After being applied in the field of rare earth smelting and separation, it has created good environmental and economic benefits.

[0029] Reduced wastewater treatment costs: 1.21m 3 / TREO*124.45 yuan / m 3 =150 yuan / REO

[0030] Reduction of new water usage: 1.21m 3 / day*35 yuan / m 3 =42 yuan / REO

[0031] The production of each ton of oxide can save 150+42=192 yuan. The company produces 50,000 tons of rare earth oxides annually, which can create economic benefits of 9.6 million yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] One or more embodiments are exemplarily described by corresponding drawings, and these exemplary descriptions and drawings do not constitute limitations on the embodiments.

[0033] Figure 1 The present invention is a process flow chart of the method for recycling impurity-removing wastewater in the rare earth smelting and separation process. DETAILED DESCRIPTION

[0034] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0035] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0036] In the embodiments of the present disclosure, the terms "upper", "lower", "inside", "middle", "outside", "front", "back" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0037] In addition, the terms "disposed", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0038] Unless otherwise stated, the term "plurality" means two or more.

[0039] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B indicates: A or B.

[0040] The term "and / or" is a description of the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.

[0042] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0043] like Figure 1 The figure shows a process flow chart of the method for recycling impurity-removing wastewater in the rare earth smelting and separation process of the present invention.

[0044] A method for recycling impurity-removing wastewater in a rare earth smelting and separation process, comprising the following steps:

[0045] Step 1: Use calcium oxide to neutralize the wash water generated during the rare earth smelting and separation process, control the pH value to ≥7, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0046] (1) Analyze the iron and zinc impurities in the wastewater, and focus on monitoring the calcium and magnesium contents.

[0047] The washing water generated in the rare earth smelting and separation process is regarded as wastewater. The wastewater is the washing water wastewater generated in the rare earth smelting and separation process, which mainly contains chloride ions, iron ions and zinc ions.

[0048] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0049] The reaction formula is as follows: Fe 3+ +3OH - =Fe(OH)3↓

[0050] Zn 2+ +2OH - =Zn(OH)2↓

[0051] Control conditions: solution pH ≥7.

[0052] Step 2: The filtrate is extracted with an extractant P 204 Calcium is removed by extraction, and the filtrate after calcium removal is recycled to the leaching step of the rare earth smelting and separation process.

[0053] At this point, the iron- and zinc-containing washing water has reached the reuse standard and can be directly reused in the leaching process of the rare earth sulfate roasting ore, realizing the recycling of iron- and zinc-containing wastewater. After the impurity removal wastewater and iron- and zinc-containing wastewater in the rare earth smelting and separation process are purified, they can be reused in the rare earth smelting and separation process to achieve the purpose of water recycling. It can be used for industrial operations and belongs to the field of hydrometallurgy.

[0054] P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P 204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process.

[0055] The organic phase loaded with calcium ions is subjected to several-stage back extraction and washing with hydrochloric acid to form a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0056] The reaction formula is as follows: Ca 2+ +2(HA)2→Ca(HA2)2+2H +

[0057] Ca(HA2)2+2HCl→CaCl2+(HA)2

[0058] Control conditions:

[0059] P 204 Concentration = 1-1.8 mol / L;

[0060] Phase ratio (filtrate: organic phase) = 1:1-10:1;

[0061] Hydrochloric acid concentration = 2-8 mol / L

[0062] The iron and zinc impurity contents in the treated wastewater are analyzed and those that meet the standards are reused in the leaching process of the rare earth sulfate roasted ore.

[0063] Example 1

[0064] Step 1: Use calcium oxide to neutralize the wash water generated during the rare earth smelting and separation process, control the pH value to 7, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0065] (1) Analyze the iron and zinc impurity content in the wastewater, and focus on monitoring the calcium and magnesium content. The data are shown in Table 1 below.

[0066] The wash water generated in the rare earth smelting and separation process is regarded as waste water. The waste water is the wash water waste water generated in the rare earth smelting and separation process and mainly contains chloride ions, iron ions and zinc ions.

[0067] Table 1 Wastewater impurity content (g / L)

[0068] <![CDATA[Cl - ]]> <![CDATA[Fe2O3]]> ZnO 5.14 0.047 0.69

[0069] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0070] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1940 mL of iron- and zinc-containing wastewater, add about 12 g of calcium oxide, and stop adding calcium oxide when the pH value of the solution is 7. Analyze the impurity content in the neutralized water. The data are shown in Table 2 below.

[0071] Table 2 Impurity content of wastewater after neutralization (g / L)

[0072]

[0073]

[0074] Step 2: The filtrate is extracted with an extractant P 204Calcium is removed by extraction, and the filtrate after calcium removal is recycled to the leaching step of the rare earth smelting and separation process.

[0075] P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P 204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is subjected to several levels of back extraction and washing with hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0076] (1) Neutralization water decalcification: organic phase (P 204 and kerosene) to extract the neutralized filtrate to control P 204 The concentration is 1.5mol / L, and the phase ratio (filtrate: organic phase) is 2:1, generating low-calcium treated wash water and calcium-loaded organic phase. The low-calcium treated wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.3g / L.

[0077] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 3 below.

[0078] Table 3 Impurity content of recycled water (g / L)

[0079] <![CDATA[Cl - ]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> ZnO 6.34 0.3 <0.001 0.09 <0.01 0.0025

[0080] Example 2

[0081] Step 1: Use calcium oxide to neutralize the wash water generated during the rare earth smelting and separation process, control the pH value to 8, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0082] (1) Analyze the iron and zinc impurity content in the wastewater, and focus on monitoring the calcium and magnesium content. The data are shown in Table 1 below.

[0083] The wash water generated in the rare earth smelting and separation process is regarded as waste water. The waste water is the wash water waste water generated in the rare earth smelting and separation process and mainly contains chloride ions, iron ions and zinc ions.

[0084] Table 1 Wastewater impurity content (g / L)

[0085] Cl- <![CDATA[Fe2O3]]> ZnO 5.14 0.047 0.69

[0086] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0087] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1940 mL of iron- and zinc-containing wastewater, add about 12 g of calcium oxide, and stop adding calcium oxide when the pH value of the solution is 8. Analyze the impurity content in the neutralized water. The data are shown in Table 2 below.

[0088] Table 2 Impurity content of wastewater after neutralization (g / L)

[0089] <![CDATA[Cl - ]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> P ZnO 6.30 3.50 <0.001 0.13 <0.01 — 0.0020

[0090] Step 2: The filtrate is extracted with an extractant P 204 Calcium is removed by extraction, and the filtrate after calcium removal is recycled to the leaching step of the rare earth smelting and separation process.

[0091] P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P 204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is subjected to several levels of back extraction and washing with hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0092] (1) Neutralization water decalcification: organic phase (P 204 and kerosene) to extract the neutralized filtrate to control P 204 The concentration is 1.5mol / L, and the ratio (filtrate: organic phase) is 2:1, generating low-calcium treated wash water and calcium-loaded organic phase. The low-calcium treated wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and a calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.32g / L.

[0093] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 3 below.

[0094] Table 3 Impurity content of recycled water (g / L)

[0095] <![CDATA[Cl - ]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> ZnO 6.34 0.32 <0.001 0.09 <0.01 0.0025

[0096] Example 3

[0097] Step 1: Use calcium oxide to neutralize the wash water generated during the rare earth smelting and separation process, control the pH value to 8, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0098] (1) Analyze the iron and zinc impurity content in the wastewater, and focus on monitoring the calcium and magnesium content. The data are shown in Table 1 below.

[0099] The wash water generated in the rare earth smelting and separation process is regarded as waste water. The waste water is the wash water waste water generated in the rare earth smelting and separation process and mainly contains chloride ions, iron ions and zinc ions.

[0100] Table 1 Wastewater impurity content (g / L)

[0101] <![CDATA[Cl - ]]> <![CDATA[Fe2O3]]> ZnO 5.14 0.047 0.69

[0102] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0103] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1940 mL of iron- and zinc-containing wastewater, add about 12 g of calcium oxide, and stop adding calcium oxide when the pH value of the solution is 8. Analyze the impurity content in the neutralized water. The data are shown in Table 2 below.

[0104] Table 2 Impurity content of wastewater after neutralization (g / L)

[0105] <![CDATA[Cl - ]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> P ZnO 6.30 3.50 <0.001 0.13 <0.01 — 0.0020

[0106] Step 2: The filtrate is extracted with an extractant P 204 Calcium is removed by extraction, and the filtrate after calcium removal is recycled to the leaching step of the rare earth smelting and separation process.

[0107] P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P 204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is subjected to several levels of back extraction and washing with hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0108] (1) Neutralization water decalcification: organic phase (P 204 and kerosene) to extract the neutralized filtrate to control P 204The concentration is 1.6mol / L, and the ratio (filtrate: organic phase) is 2:1, generating low-calcium treated wash water and calcium-loaded organic phase. The low-calcium treated wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and a calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.33g / L.

[0109] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 3 below.

[0110] Table 3 Impurity content of recycled water (g / L)

[0111] <![CDATA[Cl - ]]> CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> ZnO 6.34 0.33 <0.001 0.09 <0.01 0.0025

[0112] Example 4

[0113] Step 1: Use calcium oxide to neutralize the wash water generated in the rare earth smelting and separation process, control the pH value to 11, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0114] (1) Analyze the impurity content in the iron and zinc-containing wastewater, focusing on monitoring the calcium and magnesium content. The data are shown in Table 4 below.

[0115] Table 4 Wastewater impurity content (g / L)

[0116] Cl- Fe2O3 ZnO 4.87 0.052 0.55

[0117] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0118] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1800 mL of iron- and zinc-containing wastewater. Add about 12.3 g of calcium oxide. When the pH value of the solution is 11, stop adding calcium oxide and analyze the impurity content in the neutralized water. The data is shown in Table 5 below.

[0119] Table 5 Impurity content of wastewater after neutralization (g / L)

[0120] Cl- Ca Fe2O3 MgO SiO2 P ZnO 5.7 3.5 <0.001 0.08 — <0.0 <0.001

[0121] Step 2: The filtrate is extracted with extractant P204 to remove calcium, and the filtrate with calcium removed is recycled to the leaching process of the rare earth smelting and separation process.

[0122] P204 is mixed with kerosene as an extractant and used for single-stage extraction with the filtrate. The calcium ions in the filtrate are combined with P204, and the low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is stripped and washed in several stages using hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0123] (1) Neutralization water decalcification: The organic phase (P204 and kerosene) undergoes an extraction reaction with the neutralized post-wash water, controlling the P204 concentration to 1.4 mol / L, and the ratio (wastewater: organic phase) to 1:1, generating low-calcium treated post-wash water and calcium-loaded organic phase. The low-calcium treated post-wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and a calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.05 g / L.

[0124] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 6 below.

[0125] Table 6 Impurity content of wastewater after neutralization (g / L)

[0126] Cl- CaO Fe2O3 MgO SiO2 ZnO 5.82 0.05 <0.001 0.06 <0.01 <0.001

[0127] Example 5

[0128] Step 1: Use calcium oxide to neutralize the wash water generated in the rare earth smelting and separation process, control the pH value to 11, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0129] (1) Analyze the impurity content in the iron and zinc-containing wastewater, focusing on monitoring the calcium and magnesium content. The data are shown in Table 4 below.

[0130] Table 4 Wastewater impurity content (g / L)

[0131] <![CDATA[Cl - ]]> <![CDATA[Fe2O3]]> ZnO 4.87 0.052 0.55

[0132] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0133] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1800 mL of iron- and zinc-containing wastewater. Add about 12.3 g of calcium oxide. When the pH value of the solution is 11, stop adding calcium oxide and analyze the impurity content in the neutralized water. The data is shown in Table 5 below.

[0134] Table 5 Impurity content of wastewater after neutralization (g / L)

[0135] Cl- CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> P ZnO 5.71 3.57 <0.001 0.08 — <0.01 <0.001

[0136] Step 2: The filtrate is extracted with extractant P204 to remove calcium, and the filtrate with calcium removed is recycled to the leaching process of the rare earth smelting and separation process.

[0137] P204 is mixed with kerosene as an extractant and used for single-stage extraction with the filtrate. The calcium ions in the filtrate are combined with P204, and the low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is stripped and washed in several stages using hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0138] (1) Neutralization water decalcification: The organic phase (P204 and kerosene) undergoes an extraction reaction with the neutralization wash water to control P 204 The concentration is 1.8mol / L, and the ratio (wastewater: organic phase) is 1:1, generating low-calcium treated wash water and calcium-loaded organic phase. The low-calcium treated wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.02g / L.

[0139] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 6 below.

[0140] Table 6 Impurity content of wastewater after neutralization (g / L)

[0141] Cl- CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> ZnO 5.82 0.02 <0.001 0.04 <0.01 <0.001

[0142] Example 6

[0143] Step 1: Use calcium oxide to neutralize the wash water generated in the rare earth smelting and separation process, control the pH value to 11, remove non-rare earth ions therein, and obtain a calcium-containing filtrate after filtration;

[0144] (1) Analyze the impurity content in the iron and zinc-containing wastewater, focusing on monitoring the calcium and magnesium content. The data are shown in Table 4 below.

[0145] Table 4 Wastewater impurity content (g / L)

[0146] <![CDATA[Cl - ]]> <![CDATA[Fe2O3]]> ZnO 4.87 0.052 0.55

[0147] (2) Neutralization of wastewater containing iron and zinc: slowly add calcium oxide to the wastewater containing iron and zinc, and monitor the pH value of the solution at the same time. Stop adding calcium oxide after the pH value is qualified. Use calcium oxide neutralization method to control the pH of the reaction process to remove non-rare earth ions. The impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitation. Filter the solution, separate the filtrate and filter residue, and store the filter residue in a designated area.

[0148] Neutralization of iron- and zinc-containing wastewater: Slowly add calcium oxide to 1800 mL of iron- and zinc-containing wastewater. Add about 12.3 g of calcium oxide. When the pH value of the solution is 11, stop adding calcium oxide and analyze the impurity content in the neutralized water. The data is shown in Table 5 below.

[0149] Table 5 Impurity content of wastewater after neutralization (g / L)

[0150] Cl- CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> P ZnO 5.71 3.57 <0.001 0.08 — <0.01 <0.001

[0151] Step 2: The filtrate is extracted with extractant P204 to remove calcium, and the filtrate with calcium removed is recycled to the leaching process of the rare earth smelting and separation process.

[0152] P204 is mixed with kerosene as an extractant and used for single-stage extraction with the filtrate. The calcium ions in the filtrate are combined with P204, and the low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process. The organic phase loaded with calcium ions is stripped and washed in several stages using hydrochloric acid to become a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

[0153] (1) Neutralization water decalcification: The organic phase (P204 and kerosene) undergoes an extraction reaction with the neutralization wash water to control P 204 The concentration is 1.8mol / L, and the ratio (wastewater: organic phase) is 2:1, generating low-calcium treated wash water and calcium-loaded organic phase. The low-calcium treated wash water is discharged from the extraction equipment, and the calcium-loaded organic phase is stripped and washed with 6N hydrochloric acid to generate a blank organic phase and a calcium chloride solution that can be recycled. After this extraction step, the calcium content in the wastewater is 0.022g / L.

[0154] (2) Analyze the impurity content in the treated iron and zinc-containing wastewater. If qualified, reuse it in the leaching process of rare earth sulfate roasting ore. The reuse water data is shown in Table 6 below.

[0155] Table 6 Impurity content of wastewater after neutralization (g / L)

[0156] Cl- CaO <![CDATA[Fe2O3]]> MgO <![CDATA[SiO2]]> ZnO 5.82 0.022 <0.001 0.04 <0.01 <0.001

[0157] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A method for recycling impurity-removing wastewater in a rare earth smelting and separation process, characterized in that: include: Use calcium oxide to neutralize the wastewater generated during the rare earth smelting and separation process, control the pH value to ≥7, remove non-rare earth ions, and obtain a calcium-containing filtrate after filtration; The filtrate is extracted with an extractant to remove calcium, and the filtrate from which calcium has been removed is recycled to the leaching process of the rare earth smelting and separation process.

2. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: Analyze the iron and zinc impurity content in the wastewater, and focus on monitoring the calcium and magnesium content.

3. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: Wastewater is wash water produced during the rare earth smelting and separation process, mainly containing chloride ions, iron ions and zinc ions.

4. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: During the neutralization process of wastewater containing iron and zinc, calcium oxide is slowly added to the wastewater containing iron and zinc, and the pH value of the solution is monitored at the same time. After the pH value is qualified, the addition of calcium oxide is stopped. The calcium oxide neutralization method is used to remove non-rare earth ions in the wastewater by controlling the pH of the reaction process, and the impurities iron and zinc in the wash water are hydrolyzed into hydroxide precipitates.

5. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: The pH value is 7-11.

6. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 4, characterized in that: The hydroxide precipitates include: Fe(OH)3 and Zn(OH)2.

7. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: P 204 Mixed with kerosene as an extractant, single-stage extraction is carried out with the filtrate. The calcium ions in the filtrate react with P 204 The low-calcium filtrate is discharged from the extraction equipment and reused in the leaching process of the rare earth smelting and separation process.

8. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: The organic phase loaded with calcium ions is back-extracted and washed with hydrochloric acid to form a blank organic phase and a calcium chloride solution, and the blank organic phase is recycled.

9. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 8, characterized in that: P 204 Concentration = 1-1.8 mol / L, filtrate: organic phase ratio = 1:1-10:1, hydrochloric acid concentration = 2-8 mol / L.

10. The method for recycling impurity-removing wastewater in the rare earth smelting and separation process according to claim 1, characterized in that: The impurity iron and zinc content in the filtrate after calcium removal is analyzed, and if qualified, it is reused in the leaching process of the rare earth sulfate roasted ore.

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